The present invention concerns apparatus for the reduction of a solid feedstock comprising a metal compounds or compounds, such as a metal oxide, to form reduced products. As is known from the prior art, such processes may be used, for example, to reduce metal compounds or semi-metal compounds to metals, semi-metals, or partially-reduced compounds, or to reduce mixtures of metal compounds to form alloys. In order to avoid repetition, the term metal will be used in this document to encompass all such products, such as metals, semi-metals, alloys, intermetallics, and partially-reduced products.
In recent years there has been great interest in the direct production of metal by reduction of a solid feedstock, for example, a solid metal-oxide feedstock. One such direct reduction process is the Cambridge FFC electro-decomposition process (as described in WO 99/64638). In the FFC process a solid compound, for example a solid metal oxide, is arranged in contact with a cathode in an electrolysis cell comprising a fused salt. A potential is applied between the cathode and an anode of the cell such that the compound is reduced. In the FFC process, the potential that produces the solid compound is lower than a deposition potential for a cation from the fused salt. For example, if the fused salt is calcium chloride, then the cathode potential at which the solid compound is reduced is lower than a deposition potential for depositing metallic calcium from the salt.
Other reduction processes for reducing feedstock in the form of a cathodically-connected solid metal compound have been proposed, such as the polar process described in WO 03/076690 and the process described in WO 03/048399.
Conventional implementations of the FFC process and other electrolytic reduction processes typically involve the production of a feedstock in the form of a preform or precursor, fabricated from a powder of the solid compound to be reduced. This preform is then painstakingly coupled to a cathode to enable the reduction to take place. Once a number of preforms have been coupled to the cathode, then the cathode can be lowered into the molten salt and the preforms can be reduced. It can be highly labour intensive to produce the preforms and then attach them to the cathode. Although this methodology works well on a laboratory scale, it does not lend itself to the mass productions of metal on an industrial scale.
It is an aim of the invention to provide an electrolysis apparatus, components of an electrolysis apparatus, and a method of using an electrolysis apparatus more suitable for the reduction of a solid feedstock on an industrial scale.